1. Field of the Invention
The present invention relates to a cable-less accelerator pedal device adaptable to a vehicle, and more particularly to an accelerator pedal device including a detecting unit detecting a pedaling amount of an accelerator pedal.
2. Description of the Background Art
In a vehicle such as an automobile, conventionally, in place of an accelerator pedal device using an accelerator cable that connects a throttle valve for controlling the volume of intake air inspired in an internal combustion engine and an accelerator cable, a cable-less accelerator pedal device has been adopted, which electrically detects the pedaling amount of the accelerator pedal and controls an opening amount of the throttle valve.
In this accelerator pedal device, a rotation angle sensor is provided on a rotation shaft that functions as a supporting point of the rotational operation of the accelerator pedal, the pedaling amount of the accelerator pedal detected by the rotation angle sensor is converted into an electric signal, thereafter the electric signal is transmitted through a control part to a drive source, and the drive source controls an opening amount of the throttle valve whereby the volume of the intake air inspired in the internal combustion engine is controlled.
In this case, in such the accelerator pedal device, a return spring member for returning the accelerator pedal to a full closing position thereof is provided. When a driver lowers pedaling force onto the accelerator pedal, the accelerator pedal is returned by elastic force of the return spring member to the full closing position that is an initial position of the accelerator pedal (refer to, for example, Japanese Patent Unexamined Publication JP-A-11-343882).
On the other hand, in the accelerator pedal device that controls the opening amount of the throttle valve by the conventional accelerator cable, when the driver depresses on the accelerator pedal against the elastic force of a return spring provided on the throttle valve, reaction force is produced, and sliding resistance by the accelerator cable is generated when the driver treads on-and-off the accelerator pedal. In the cable-less accelerator pedal device, the return spring member is provided in place of the return spring provided on the throttle valve, whereby the reaction force when the driver treads on the accelerator pedal is produced. However, the sliding resistance by the accelerator cable is not generated when the driver tread the accelerator pedal on-and-off.
As a result, when the driver changes a vehicle from a vehicle adopting the conventional accelerator pedal device to a vehicle adopting the cable-less accelerator pedal device, the driver feels differences in operation of the accelerator pedal. Therefore, the cable-less accelerator pedal device adopts a hysteresis generation mechanism that causes intendedly resistant feeling resemblant to the sliding resistance by the accelerator cable (refer to, for example, Japanese Patent Unexamined Publication JP-A-2002-283872)
In the JP-A-11-343882, it is necessary to provide the rotation angle sensor for detecting the pedaling amount of the accelerator pedal (that is, the rotation amount thereof) so as to be coaxial with the rotation shaft that supports the accelerator pedal. Therefore, there is a problem that the dimension in the width direction that is nearly orthogonal to an axis of the accelerator pedal in the accelerator pedal device increases, which makes the size of the accelerator pedal device large. Specifically, the width dimension near the rotation shaft in the accelerator pedal device increases.
Further, the rotation angle sensor is provided, for example, between the accelerator pedal that is a rotary part in the accelerator pedal device and a body that is a fixed part. Therefore, there is required adjustment works such as position-matching with the accelerator pedal and the body. Therefore, there is a problem that the attachment work of the rotation angle sensor becomes complicated, which causes the increase of the manufacturing pedals of the accelerator pedal device. Particularly, in case that a Hall element type sensor is adopted as the rotation angle sensor, when a magnetic (for example, permanent magnet) provided for the accelerator pedal is detected by the Hall element, there is a problem that detection accuracy lowers because of position mismatching between the magnetic and the Hall element that is a detection part and unsteadiness in the radial direction that is nearly orthogonal to the rotary direction.
Further, since the rotation angle sensor converts the pedaling amount of the accelerator pedal into the rotation angle (rotation amount), it must have rotation stroke according to the rotation amount of the accelerator pedal. Therefore, there is fear that in the accelerator pedal having large rotation amount, the rotation angle sensor will be made large correspondingly, and the structure of the rotation angle sensor will be complicated.